Truck with support legs

ABSTRACT

Narrow aisle truck that on each side includes two forwards extending support legs ( 1, 2 ), which each are provided with two support wheels ( 4, 5 ). The two outer support wheels are displaced somewhat to the rear in relation to the inner ones and in the corner space outside the inner ones and in front of the outer support wheels lateral guide wheels ( 6 ) are arranged.

[0001] The present invention concerns an arranging of support leg wheelsfor the achieving of increased stability at so called narrow aisletruck. Trucks of this kind move essentially forth and back in narrowaisles that are only marginally wider than the truck itself. In order toreduce or rather eliminate the risk that the truck bump into the racksalong the aisles the support legs are in their front ends provided withlateral guiding wheels intended to fend off against rails arranged alongthe floor. Since racks and trucks are getting increasingly higher anincreased stability is desirable. The object of the invention is toachieve this.

[0002] In accordance with the invention an improved stability of thetruck is achieved by arranging two support wheels in each front end ofthe support legs, with the outer of these displaced somewhat to the rearso that the laterally guiding wheels can be placed in front of the outersupport wheels and outside the inner support wheels on each support leg.

[0003] With the invented arrangement of the support wheels and thelaterally guiding wheels the stability of the truck is improved inseveral ways. To start with the support wheels and then in particularthe outer ones can be placed as far out as the width of the aisle allowswithout the lateral guide wheels being in the way of this. Nor do thelateral guide wheels infringe on the wheelbase of the truck or makesthis longer. In other words the lateral guide wheel on each side isaccommodated without restricting the total wheelbase or the track widthof the outer wheels. At the same time the lateral guide wheels arearranged in the front end of the truck, where they also function best,protruding a small measure forward as well as well as laterally. Sincethe inner wheels are located as far forward as the construction allowsmaximum stability against a tilting forward is achieved.

[0004] Since the outer wheels at the same time can be located as far outas the aisle allows maximum stability against lateral tilting movementsis achieved at the same time. Possible lateral tilting movementsnormally do not occur exactly laterally but perpendicular to a linethrough the outermost support points on the tilting side, that is a linethrough the outer contact point of the outer support wheel and thecontact point of the rear steering and driving wheel if the truck onlyhas one rear wheel. If the truck is equipped with two closely or spacedmounted driving and steering wheels the tilting line passes through thecontact area of the wheel located on the side towards which tiltingtakes place. Irrespective of the number of wheels or the width of theseor track width the widening in the front end result in an outwarddisplacement of the tilting line. That is the distance to the center ofgravity increase in the horizontal plane, which is the same thing as anincreased stability. A fact is that since the track width when severalrear wheels are used or the width of the rear wheel of this if it isalone normally is essentially less than the track width of the outerwheels of the support legs also the displacement of the outer supportleg wheels to rearward will contribute to a displacement of the tiltingline out from the center of gravity, that is a further increasedstability.

[0005] In this way the risk of lateral tilting of the truck is reduced,when it for instance is moved between different narrow aisles.

[0006] With the wheel arrangement according to the invention not only anincreased stability is achieved but the relative position of the supportwheels give each support leg an increased contact when the truck wheelspass joints in the ground. Either one or the other wheel for eachsupport leg will be supported against the ground when the other wheelpass the joint. In this way the oscillation tendencies lengthwise of thetruck are reduced at movement and furthermore a more silent and smoothrun is obtained when passing joints. This smother run reduce the strainsin the truck and reduce the discomfort of the driver who may be high upand at a millimeter movement of the support legs will be subjected to aswing of several centimeters.

[0007] Further advantages and characteristics of the invention areapparent from the patent claims and the following description of anembodiment of the invention. On the enclosed drawing an embodiment ofthe invention is shown schematically in perspective.

[0008] The narrow aisle truck shown in the drawing include two supportlegs 1 and 2, which in their outer ends are provided with a frontsupport wheel 4 and a rear support wheel 5. The support wheels aredisplaced lengthwise so that the inner support wheel is located more tothe front and the outer support wheels 5 somewhat behind the front ones.In the space outside of the inner support wheels and in front of theouter support wheels (that is the front corners of the truck) lateralguide wheels 6 are arranged so that they protrude somewhat outside theframe lengthwise as well as laterally for contact with rails, not shown,for lateral guided motion of the truck. The lateral guide wheels arejournaled on vertical axles fastened in the two support legs (not shownfor reasons of clarity).

[0009] In the shown case its is a narrow aisles truck provided with ahigh structure in several parts (of which only the lowermost is shown),and a liftable drivers cage in this (not shown), that is a truck with avery high center of gravity, which means that the stability has a verylarge influence on maximum load, maximum speed and maximum retardationand acceleration.

[0010] The wheel device in accordance with the invention can also beused for other trucks than the one described above for narrow aisles, asfor instance mid-steered where an essentially improved stability isobtained.

[0011] Even if the wheel device in accordance with the invention hasbeen invented based on the specific needs that are present at narrowaisles trucks one can consider using the concept with displaced supportleg wheels to improve stability also for other trucks than those withlateral guide wheels.

1. Arrangement at narrow aisle truck, which on each side has forwardextending support legs (1, 2), which each are provided with two supportwheels (4, 5), characterized in that the two outer support wheels (5)are displaced somewhat to the rear in relation to the inner ones (4) andthat in the space outside of the inner ones and in front of the outersupport wheels lateral guide wheels (6) are arranged.